Heat exchangers for recovering heat which would otherwise be wasted from flue or exhaust gases are well known. In these prior art devices the flue gases flow past tubes through which the air to be heated is flowing and the hot flue gases heat the air which may then be used for heating either the furnace room or some other room. A problem with these waste heat recovering systems lies in the fact that the exterior surfaces of the tubes containing the air to be heated are exposed to the hot exhaust gases and therefore become dirty from soot and carbon which greatly detracts from the efficiency of the unit. As a result, they must be frequently cleaned.
The cleaning of such tubing in the previous waste heat recovery systems has been a difficult task because of their inaccessibility and their awkward location. This problem was recognized and an effort made to solve it in U.S. Pat. No. 2,882,023 issued to Salvatore Rizzo on Apr. 14, 1959 inasmuch as the tubes for carrying the air to be heated are removable as a unit from the heat box for cleaning. However, because of the removability of the tubes from the heat box, inadequate sealing results, so that the exhaust gases can escape into the furnace room and into the air being heated as well. The units are made of sheet metal and tight fits cannot be obtained without the use of positive seals to prevent the escape of the exhaust gases.
The present invention solves this problem by constructing the fresh air tubes into a unitary assembly that can be slid into and out of the heat box as a unit while also providing easily installed and removable seals that seal the tubes from the interior of the heat box and seal the heat box itself so that hot exhaust gases from the furnace or boiler cannot escape except through the chimney.
A general object of the present invention is to provide an improved heat exchanger for recovering heat from the flue or exhaust gases of a heater which would otherwise be wasted.
A further object of the present invention is to provide an improved heat exchanger for extracting heat from flue gases which can be readily disassembled for cleaning and yet is tightly sealed to prevent any escape of the hot gases from the flue.